1. Field of the Invention
The subject invention relates to a color imaging system for reproducing colors of incident light.
2. Description of the Prior Art
The ability of the human eye to distinguish color results from stimulating three types of retinal receptors, i.e. cones, contained within the retina of the eye. The three types of cones contained in the eye are typically referred to as L-cones, M-cones, and S-cones. Each of the three types of cones is responsive to a specific wavelength range. For example, L-cones have a peak sensitivity in the orange region of the visible spectrum. M-cones have a peak sensitivity in the green region of the visible spectrum. S-cones have a peak sensitivity in the blue region of the visible spectrum and are sensitive to light having a wavelength as small as 380 nm. The various wavelengths of light stimulate the cones, which cause each cone to generate an electrical impulse. The electrical impulses are combined and are communicated to the brain via the optic nerve. Based on the electrical impulses, the brain distinguishes the color of light received through the eye.
Color imaging systems are used to reproduce the colors of images. Traditional color imaging systems include image sensors having red, green and blue sensor pixels that sense red, green and blue incident light, respectively. The sensor pixels can be arranged in a vertical relationship with one another, as disclosed in U.S. Pat. No. 5,965,875 to Merrill, or the sensor pixels may be disposed in a horizontal arrangement with one another, as disclosed in U.S. Pat. No. 3,971,065 to Bayer. Each sensor pixel delivers a signal to a color display module. The color display module emits light intended to reproduce the colors sensed by the sensor pixels.
The color imaging system includes a plurality of light emitting devices for emitting light. Traditional color imaging systems utilize red light emitting devices for emitting red light, green light emitting devices for emitting green light, and blue light emitting devices for emitting blue light. For example, US Patent Application Publication Number 2004/0100437, assigned to Hunter et al. and published on May 27, 2004 (hereinafter referred to as Hunter '437), shows a color display system that uses a light emitting diode (LED) as a blue light emitting device having peak light emission in the range of between 400 and 450 nm. LEDs and other phosphor based light emitting devices are known to emit light at a very wide band of wavelengths. The full width at half maximum (FWHM) is a measure of the range of wavelengths emitted by a light source. For example, LEDs generally have a full width at half maximum (FWHM) value of between 20 and 50 nm. In other words, much of the light emitted by a LED has a wavelength of greater than 25 nm from the peak emission wavelength of that LED. In summary, the range of wavelengths actually emitted by even the most focused LED light sources will vary significantly from that LED's peak emission wavelength.